The present invention relates to an illumination light supply apparatus for endoscope.
In the usual endoscope system, a connector which is coupled to the end of an universal cord, in which a light guide formed of an optical fiber or the like is inserted, is removably connected to a socket of a light supply apparatus. When the connector is connected to the socket, light from a light source is incident on the end surface of the light guide penetrating and projecting from an opening of the socket. The incident light is transmitted through the light guide to the endoscope to illuminate an object such as the surface of a cavity inside the human body.
The light source mentioned above generally includes a high brightness lamp which cannot recover to the "on" state right after it is turned off. The high brightness lamp accommodated in the light supply apparatus is, therefore, normally held "on" during the use of the light supply apparatus. When the connector is disconnected from the socket while the lamp is "on", however, the light from the lamp leaks to the outside of the light supply apparatus through the aforementioned opening. When this kind of light beam reaches the eyes, of the doctor or patient, he or she is dazzled by the light beam. Besides, this light beam is prone to the danger of radioactive radiation or like adverse effects.
U.S. patent application Ser. No. 195,440 discloses a light supply apparatus which can solve the above problems. With the light supply apparatus, when the light supply apparatus is disconnected from the socket, the quantity of light emitted from the light source and reaching a socket opening is automatically reduced to a predetermined level to solve the above-mentioned problems to a certain extent. However, with the apparatus, the state of coupling between the connector and socket is detected as a change of the state of a mechanical switch member such as a contact switch, becoming either on or off. The mechanical switch member has a voltage-bearing bare metal pin which is exposed at the outer surface of the socket from which the connector is disconnected. Therefore, the operator is prone to the hazard of electric shock in case if the operator occasionally touches the exposed metal pin. Further, depending upon the environmental conditions, the exposed portion of the metal pin is liable to be corroded by oxidization and covered by an undesired oxide film. In such a case, a contact failure of the contact switch member is occurred, whereby detection of the state of coupling between the connector and socket can no longer be done.